Cushioning mechanism for power hammers



Jan. 3, URBANEK ET L CUSHIONING MECHANISM FOR POWER HAMMERS Filed Mayl0, 1928 JIJ/1 U5 Urlo@ nek Patented Jan. 3, 1933 UNITED STATES aUiIusURRANEK, orvimvvn, AUSTRIA, AND ARTHUR scHNEIDuR,` or DussRrDoRr,

'Y 1 y GERMANY Y PATENT .o1-*FICE cusmolvnv'crv MEcHANrsM roR :POWER-HAMMRRS Application filed Hay 10, 1928, Serial No. 276,577, and inAustria May 31, 1927'.-` f

'.This invention relates to a hydraulic brak forthe tup rod of drophammers. v Drop hammers are known in which the tup rod, forexample,board, toothed rack, piston rod together -with the piston and the likeare movable relative to the tup, and in which the momentum of the rodlaccumulated during the drop is dissipated byfa brake. Drop hammersarefurther known in which the momentum ofthe rod movablerelatively tothe tup is acciunulated in a steam 4orairchest of the tup cylinder, andin which the upward movement of the rod is checked by a hydraulic brakein the tup, which brake is only effectiv duringsaid upward movement.

Both of these constructions have disadvantages. The first mentionedconstruction leads by the use of elastic driving medium such as, forexample, steam, compressed air or the like to undesired high relativespeeds between 'rod and tup causing the carrier owing to its violentstoppage to be adversely eected, whilst the ,last mentioned constructionrequires a very long path of retardation which mechanically -isunsatisfactory.' v

The present invention consists in an appropriate combination of featuresof both constructions, in which a double hydraulic brake is employed,one braking action being chiefly eective during the downward movemento-f the tup, whilst the other is'eifective during the upward movement.

The invention is illustrated in the accomanying drawing in which thefigure is a ragmentary vertical sectional view of one form of theinvention.

A hydraulic cylinder 2 is arranged in the l tup l and contains discpistons 4 and 5 of a plunger piston 3. The tup rod of any desiredconstruction, for example, a piston rod is ixedly connected to theplunger 3. In the drawing the piston is illustrated in its highestposition. In this position the tup is supported by means of the cylindercover on a collar 6 formed on the plunger piston 3. Ports 9 are formedin the piston 4 for the free passage of the braking liquid as a plate 7for controlling them is held by a spring 8 in its highest position.

The illustrated position of the piston remains unchanged-during the fallof thetup. When the tup delivers its blow and Vis retarded, then thepiston moves downward and the braking fluid is 4introduced around thepiston 5 and alsothrough and around the piston 4. As in the usualdistance of drop, the speed of the tup `end is about 6.5 metres pervsecond, and the liquid is forced at a great speed up through the ports9. yIf thefplate valve 7 were displaced on its seat against the 60piston 4, then Vsimultaneously it 4would be fo-rced upwardly at a great.speed Aand thereby -receive injury by forceful Contact with the collar 6or other limiting arrangement. This danger is avoided however by holdingthe plate valve 7 olf its seat against the pistony 4 by means of thespring 8, thereby rendering the raising of the valve by the liquidunnecessary.

The breaking liquid in its passage round and through the pistons isconsiderably throttled, so thatthe necessary super-pressure forretardation of the rod and dissipation ofv energy is produced.

The liquid displacedby the plunger piston 3 passes through holes 10 intothe air reservoir provided in the interior of said piston.

In order to keep the braking force approxi-` mately constant in spite ofthe vdecreasing speed of the rod the lower part of the cylinder. isreduced, so that the outlet cross section for theliquid displaced bythepiston 5 constantly decreases. The rod therefore will from the moment ofthe blowjmake an approximately uniformly retarded movement until itcomes to rest. y Y

As soon ,as the 4operation of the tup takes place, the braking liquidwill pass downwardly through the ports 9, and close the valve byovercoming the tension of the spring which is made only slightly morethan the weight of the valve. Grooves l1 are provided in the cylinderwall for the overiow. As these grooves however are o-f small crosssection the piston 4 upon its upward movement is met` with a .powerfulresistance, and can only assume a small relative speedagainst the tup.As,-moreover, the grooves merge out at the top, gentlecontact of theco-llar 6 with lthe 100 cylinder cover is ensured.

Upon the upward movement of the rod the lower piston 5 is non-eective,because the large cross section liberated by it cannot produce anypreceptible throttling effect during the small upward speed of the rod.

According as the plunger' piston' 3 ascends, so does the braking liquidreturn from the air reservoir into the brake cylinder 2.

Then the rod drops there is no need lfor the piston e to fit completelytight owing to its great speed, but it is well for it to do so uponascent because only then will the relative movement of the rod againstthe tup be able to be regulated by thelongitudinal profile of thegrooves ll, or the cross-section of holes l5 orl grooves 16 and soforth.

Y Ve claim: Y j

' l. A cushioning device, comprising a chamber containing a liquid, aplunger movable in said chamber and having a cavity communicating withsaid chamber, said chamber presenting a steadily decreasing Crosssectional area to the plunger in its downward movement, said plungercomprising two-iiange-like projections dividing the chamber into threesections, the upper projection having ducts to establish communicationbetween the two upper sections and a check valve for said ducts.

2. A cushioning device, comprising a chamber containing a liquid, aplunger movable in said chamber and having a cavity communicating withsaid chamber, there being ducts to establish communication between thecavity and the end section of the chamber, a collar on said plungertovlimit the' upward movement thereof within the chamber,said chamberpresenting a steadily decreasing cross sectional area to the plunger inits downward movement, said plunger comprising two ydisc shapedprojecting flanges dividing the chamber into three sections, the upper.iiange having ducts to lestablish communication between the two upper isections, and ai check valve for said last mentioned ducts, said checkvalve comprising a resiliently supported disc adapted to seal saidducts.

3. A'cushioning device, comprising a liquid containing chamber having anupper cylindrical portion of reduced cross sectional area, a lowerconical portion of reduced cross sectional area and a mid-portion havinggrooves in itsV wall, a plunger movable in said chamber and having acavity communicating with said chamber, said chamber presenting asteadily decreasing cross sectional area to the plunger in its downwardmovement, said plunger comprising two flange-like projections dividingthe chamber into three sections, the upper projection having ducts ytoestablish communication between the two upper sections, anda check valvefor said ducts.

4. A cushioning device, comprising a liquid containing chamber having anupper cylindrical portion of reduced cross sectional area., a lowerconical portion of reduced cross sectional area and a mid-section havinggrooves in its wall, a plunger movable in said chamber and having acavity communicating with said chamber, there being ducts to establish`communication between the cavity and the mid-section of the chamber,avcollar on said plunger to limit the upward Inovement thereof withinthe chamber, said chamber presenting .av steadily decreasing crosssectional area to the plunger in its downward movement, said plungercomprising two disc shaped projecting iianges dividing the chamber intothree sections, the-upper flange having ducts to establish commu-vnication between the two: upper sections, and a check valve for saidllast mentioned ducts', said check valve comprising a resilientlysupported disc adapted to'seal said ducts.

5.' A cushioning` device for power hammers, Vcomprising a liquidcontaining cham!- ber, a plunger movable-finl said chamber and having acavity communicating with'.- the chamber, said chamber presenting asteadily decreasing cross sectional area to theplunger in-its upward.andi in its-'downward movement, said plunger comprising two flangelikeprojections dividing the `chamber into three sections, the upperprojection having ducts to establish communication between the' upperand mid-chamber sections, and -a check valve to seal saidducts.

Signed at Vienna, Austria, this-'20th day- Of April, 1928;- Y

n J. URBANEK. Signed at Cologne, Germany, this 25thdayv ofl April, 1928.ARTHUR SCHNEIDER.

